1. Field of the Invention
The present invention relates to cutting tools, and in particular cutting tools for agricultural mixers, and more particularly pertains to a new agricultural mixer auger cutting blade for providing a durable cutting blade with improved impact and wear resistance.
2. Description of the Prior Art
The use of cutting tools, and in particular cutting tools for agricultural mixers, is known in the prior art.
Agricultural mixers which chop and mix grains for use as livestock feed have been manufactured and used for several years in the United States and Europe. These mixers are predominantly used for chopping relatively soft materials such as grains. Conventional blades employed in these mixers arc typically constructed from a single piece of steel having a uniform material character throughout the entire blade. Such conventional blade construction, even when used for chopping and mixing grain and other relatively soft materials, has a relatively limited life span of only about 200 hours of operation before requiring replacement.
Relatively harder materials, such as, for example, used turkey bedding straw (and the turkey dung mixed in with the bedding straw) have been increasingly added to grain placed in the mixer for chopping to enrich the nutritional mineral levels in the mixture which is used as a livestock feed. Some of the minerals in the turkey dung can cause portions of the turkey bedding straw to harden to a hardness that is substantially harder than the grains placed in the mixer. In fact, the hard portions of the straw can become harder than concrete or volcanic ash, which makes the turkey bedding straw significantly more abrasive on the blades of a mixer than the much softer grains chopped in the mixer. Conventional blades used in mixers have exhibited a significantly reduced life span when hard materials such as turkey bedding straw is chopped in the mixer. The life span for blades used in mixers where a significant amount of used turkey bedding straw is mixed is substantially reduced, to about 30 hours of operation, before the blades require replacement. This shortened life span makes operation of the mixer much less economical.
The blade of the invention described in our U.S. Pat. No. 5,823,449 utilizes carbide cutting teeth inserts for increasing the life span of the blade. The blade described in U.S. Pat. No. 5,823,449 is highly suitable for use in devices where the cutting edges and surfaces of the cutting teeth are moved in a direction that is substantially perpendicular to the orientation of the cutting edge of the blade. One example of such a device is on a "vertical" livestock feed mixer, where the axis of the mixer auger is substantially vertically oriented. As a result of this perpendicular movement, the cutting edges of the cutting teeth primarily strike the material to be mixed in a direction that is substantially perpendicular to the cutting edge, and the impact of the cutting is transferred to the blade by the cutting teeth in a direction substantially perpendicular to the edge of the blade. In the case of our invention described in U.S. Pat. No. 5,823,449, the impact of cutting is transferred from the cutting teeth insert in a direction perpendicular into the insert mounting surface on the blade.
Other types of devices, such as, for example, "horizontal" livestock feed mixers, move the blades in a manner such that the cutting edge of each of the cutting teeth does not strike the material at an orientation perpendicular to the cutting edge. Instead, the cutting edge of the cutting teeth strikes the material at an angle that varies significantly from the perpendicular to the cutting edge, in what may be characterized as a "slashing" orientation. As a result of this movement, a significant component of the impact of the material against the cutting edge is directed in a direction parallel to the cutting edge, rather than a direction primarily perpendicular to the cutting edge. The magnitude of the impact forces applied parallel to the cutting edge is further increased by the design of some blades where the cutting edge has an undulating or scalloped shape with alternating peaks and valleys. The direction of the forces applied to the cutting edge of these blades thus presents substantially different problems from the devices where the material is struck in a primarily perpendicular manner. The transfer of the impact force from the teeth inserts to the blade at a non-perpendicular angle to the blade surface changes the character of the forces on the mounting between the insert and the blade. As a result, the manner of mounting the cutting teeth inserts on the blade as described in U.S. Pat. No. 5,823,449 is not most ideally suited for use in devices where the cutting edge is not moved in a direction substantially perpendicular to the cutting edge.
In these respects, the agricultural mixer auger cutting blade according to the present invention substantially departs from the conventional concepts and designs of the prior art, and in so doing provides an apparatus primarily developed for the purpose of providing a durable cutting blade with improved impact and wear resistance.